Considering the evolving needs of time metrology and the convenience of allowing the contributing laboratories access to a realization of UTC more frequently than through the monthly BIPM Circular T, the Time Department implemented a rapid realization of UTC which has been officially published every week since July 2013. UTCr gives daily values of [UTCr  UTC(k)] for a subset of laboratories contributing data to the monthly Circular T. Participation in UTCr is voluntary, provided that the laboratories commit to submitting data daily to the BIPM.

Although the results of UTCr are consistent with those in Circular T at the level of a few nanoseconds, BIPM Circular T remains the unique source of traceability to UTC.

Rapid UTC

Daily values of the differences between UTCr and its local representation by the given laboratory